Elastic-fluid turbine



' G. B. WARREN ELASTIC FLUID TURBINE Filed Dec- 22- 19.23

ywmh j ney- His Abbor Patented Feb. 17, 1925.

UNITED STATES ,7 1,526,814 PATENT orries.

GLENN B. WARREN, OF S CHENECTADY, NEW YORK, ASSIGNORTO- GENERAL ELECTRIC COMPANY, A CORPORATION 013 NEW YORK.

ELASTIC-FLUID TURBINE.

Application filed December 22, 1923. Serial N01 682,325.

To all whom it may concern: 5

Be it known that I, GLENN B. WAnRnN, a citizen of the United States, residing at Schenectady, in the county.of Schenectady,

State of New York, have invented certain new and useful Improvements in Elastic- Fluid Turbines, of which the following is a specification.

In building high, speed, large capacity turbines, the buckets in the last few stages become quite long which means that there is considerable difference in peripheral speed between the roots of the buckets and their tips. The result is that if in an impulse turbine thecentral portions of the buckets are running at a speed correct for most efficiently extracting the energy from the elastic fluid issuing from the nozzle then the root portions are running too slow for highest efficiency and the tip portions are run ning too fast for highest eificiency.

The object of my invention is to provide an improved means for overcoming this difliculty due to the difference in speed be tween the roots and the tips of long buckets whereby, better efliciency will be obtained.

In the design of elastic fluid turbines, it has been found that in order to absorb the same quantity of energy from an elastic fluid a pure reaction combination of nozzle and bucket must run at a speed about 40% greater than a corresponding impulse combination. This means that if the root end of a bucket is running at about the right speed to operateas an impulse bucket, the tip end would be running at a speed adapted for either total or'partial reaction operation. In carrying out my invention, I take advantage of this fact, and according to my invention in the case of long buckets I so shape the fluid passages of the nozzle-bucket combination that they operate as an impulse combination at their inner or root ends and as either a artial or total reaction combination at them outer or tip ends. This may be accomplished in several ways. It may be accomplished by warping the nozzle partitions so as to give a larger discharge angle at.

the radially outer ends of the nozzles than at their radially inner ends, or it may be accomcombination of these two means may be used if found desirable.

In the drawing Fig. l is a radial 'sectional view through a nozzle-bucket combination embodying my invention; Figs. 2 and 3 are sectional views taken .on lines 2 -2 and 33' respectively in.Fig. 1;- and Figs. 4: and 5 are views similar to Figs. 2

and 3 ofa modification.

Referring to the drawing, 1 indicates a turbine shaft carrying rotor elements 2 and 3 on which are the bucket. rows {and 5, .and 6 indicates the turbine casing carrying the stationary fluid directing nozzles 7. Only a fragmentfof' the turbine is shown, the portion illustrated being adjacent stages at the low pressure end of the machine. In the present instance, the nozzles are formed in a diaphragm 8. .They receive elastic fluid from bucket row 4 and deliver it to bucket row 5. The construction of the nozzlebucket combination comprising nozzles 7 and buckets 5 is such that the radially inner portion of the combination operates as portion the combination operates partiallyor wholly as a reaction combination the change being gradual from the one .to the other. As illustrated in figs. 2 and 3 this is accomplished by warping the nozzle partitions 9 so that they have greater dis: charge angle at their outer ends than at their inner ends, the exit angle 1) of the buckets remaining the same. At their inner ends the nozzles have the discharge angle a as shown in Fig. 2 while at their outer ends they have the discharge angle a plus an amount at. As illustrated in Figs.4 and 5 Iaccomplish' the same result by leaving-the nozzle discharge angle a the same and varying the. exit angle of the buckets from their inner ends to their'outer ends,

the-inner ends having an exit angle 6 as vlndlcated 1n Flg. 4 and the outer ends havmg an exlt angle 6 minus an amount 3 as shown in Fig. 5.

Since the outer ends of the buckets have a certain amount of reaction there is of course, some-drop'in pressure across them and to limit the leakage I provide suitable packing means as indicated at 10. At 11 is indicated the usual diaphragm packing.

By my invention I provide a nozzle-bucket combination which takes care of the differ ence in speed between the roots and the tips of the buckets and thereby gives better efliciency for the combination than has been obtained heretofore. It will be understood that I am using the ternrnozzle in a broad sense and intend to include thereby any stationary fluid directing element.

What I claim as new and desire to secure by Letters Patent of the United States, is

1'. In an elastic fluid turbine, a nozzlebucket combination wherein the fluid passages are soshaped that the radially inner portion operates as an impulse turbine and gradually changes to operate as at least a partial reaction turbine at the radially outer portion, the change being made commensurate with the difference in speeds at which the radially inner and outer portions of the buckets rotate.

2. In an elastic fluid turbine, a nozzlebucket combination wherein the discharge angle of the nozzles increases from the radially inner portion to the radially outer portion by an amount such that the combination changes from impulse operation at the radially inner portion to at least partial reaction at the outer portion. the change being made commensurate with the difl'erenci-w in speed at which the radially inner and outer portions of the buckets rotate.

In witness whereof, I have hereunto set my hand this 21st day of December. 1923.

GLENN B. WARREN. 

